Electrical measuring instrument.



i W. E. BEEDE. ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED MAR. 22, 1911.

Patented May 28, 1912 WITNESSES ATTORNEY W. E. BEEDE.

ELECTRICAL MEASURING INSTRUMENT.

APPLIGAT ION FILED-MAR. 22. 1911.

Patented May 28, 1912.

7 2 SHEETS-SHEET 2.

I INVENTOR. 7 41 4;; 5, 142x1 4 7 0 q/VE Y WITNESSES w (M nNIT D STATES PATENT OFFICE.

WALTER n. IBEEDE, on NEW YORK, n. Y

ELECTRICAL 'MEA SURING INSTRUMENT.

To all whom may concern 7 Be it known that I, WALTER E. BEE-DE, a citizenof the United States, residing in the borough of Manhattan, city of New York, in the county of New York and State of New York, have inventedcertain new and useful Improvements in Electrical Measuring Instruments, ofwhichthe following is aspecifica'tion, reference being had therein 19 to, the accompanying drawings, forming part thereof. 1

My invention. relates generally to electrical measuring instruments of that class in.

which a'magnetic shunt or=magnetic bridge is employed to adjust or otherwise modify the magnetic field of the instrument; and

my invention more particularly relates to galvariometers of the'DArsonval type. The general objects of my invention are 0 accuracy of indication, simplicity of conysi'ruction, and inexpensiveness of manufacture.

or compensating means upon the armature:

Another object is to provide an improved damping device for the armature.

, Another object of my invention is to re- 5 duce the numberof parts by combining a large number of functions in a few parts.

Other objects of my inventionwill hereinafter appear. Q

My invention includes means, such as a 0 magneticbridge for the opposed ,poles of a,

field magnet, forming a gnagnetic shunt around the end-of a rotative coil or other form ofpivoted armature so that the armature will not be directly aflected. thereby) 5 and modifying andproviding for adjusting the intensity or density of the magnetic field by which. the armature is influenced, enabling the magnetic force to which the armatureis exposed to be corrected from time to 0 time to harmonize or agree with the cali u brations of the instrument, particularly to correct any false indication due to the gradual weakening of a permanent field magnet. 5 Also, as a feature of my magnetic bridge constitutes a pivotal suplated from invention, the

1 port for the armature,the magnetic adjustment being effected by means ofiadjustable pole-pieces carried by the bridge, the'latter eihg spaced from and nonmagnetically supported on the magnet. I

My invention also includes a damping de- .'vice combined with the magnetic shunt; for example, a damping disk rotatively carried by the armature and adapted to move between the magnet poles and one or more ad- Specifieation' of Letters Patent. Ph,tented May ,1912, i licatlon filed March 22, 1911. Serial No. 616,098.

justable pole-pieces carried by the magnetic bridge.

.My invention also includes several features of construction and combinations of parts, as :Vill appear from the following description. I

I shall now describe the gali anoineter illustrated in the accompanying drawings and embodying my invention and shall thereafter point out my invention in claims.

. Figural is a rear-view of the instrument with the casing partly broken away. Fig.2 is-a front view, partly in section on a plane indicated by the line 22 in Fig. 4. Fig. 3

is a partial section on a plane indicated by the line 3-3 of Fig. 4, as viewedrfrom above.

Fig. 4 is a side viewas seen from below in Fig. 2, with the top part of the casing removed andother parts-broken away. Fig. 5 is a. partial vertical section on a plane indicated by the line 5-5 of Fig. 4 as viewed from the right. I

Thegalvanometer illustrated in thedrawings has a bar 6 of soft iron extending across or bridging theopposed poles of a permanent field magnet 7, the bar 6 being located I atthe end and forming a magnetic bridge or magnetic shunt around the end of'a rotative armature coil 8 located in the magnetic field of the magnet- 7 and shown as placed between the spaced magnetic poles. The bar 6 is shown of curved form to correspond to the curvature of the ring shaped magnet 7, and is. spaced from and supported on the magnet by non-magnetic'blocks 9 and screws I0; and thebridge barb is'electrically insu the magnet 7 by insulating rings 11.

Thebridge bar 6 carries adjustable iron pole pieces' 12, a pole-piece for each magnet pole, shown having inner heads provided. with stems adjustably screw-threaded through the bar 6, the outer ends of the stems ,having therein screw-driver notches, as shown, for'conveniently efiecting adjustment of the pole-pieces .lZ t-o or from the corresponding magnet poles, to thereby diand tot-that extent away from the armature coil 8. As the bridge 6 is located at the end of the rotutive coil 8, substantially in axial line therewith, the coil 8 will not be directly atlected by the magnetic bridge 6 and its pole-pieces 12, but will be indirectly affected through the weakening to a greater or less extent of the magnetic field to which the coil 8 is exposed and to which it is respon sive. Should the permanent magnet 7 become weakened, the pole pieces 12 may be accordingly adjusted farther away from the magnet poles, to then divert lessof the magnetic force and thus proportionately increasc-or ratherrestore--the magnetic density of that portion of the field between the magnetic poles and occupied by the armature coil 8, thereby compensating for the loss in magnetism of the magnet 7 and correcting the indications of a pointer 13 carried by the coil 8 in reference to a calibrated dial ll. The pole-pieces 12 may thus be conveniently adjusted by inserting a screwdriver through openings provided for .the purpose in the base-plate 15 of an inclosing casing for the instrument, these screw-driver holes being normally covered by a relative cowr-plate 16 pivoted on the base-plate 15, thus rendering it unnecessary to take the instrument apart or to remove any part of it in order to cfi'ect this adjustment. By means of such magnetic adjustmcnt: the inst rumcnt may at any time, by comparisonwith a standard instrument, be brought back to its correct indication as originally calibrated. The bridge bar 6 also serves as a pivotal support or axial support for the relative armature coil 8, thus simplifying the construction and reducing the number of parts.

The bar 6 carries a step bearing 17 in which is pivoted the conical end of an arbor 18 on which is mounted a non-magnetic coilframe or bobbin 19 upon which in turn is wound the armature coil 8. The other end of the arbor 18 is similarly pivoted in a. step -bearing 20 carried by a non-magnetic arborsupport 21 secured to the adjacent side of the magnet 7 by screws 29; and elcctricall y insulated from the magnet by insulating rings 23. The pointer '13 is also mounted directly on the arbor 18 so as to partake of the movement of the coil 8 and its frame 19.

The pointer 13 is brought, to the zero indication by means of. usual opposed adjustable hair-springs 24 which also serve as leads for electric current to and from the coil 8. At their inner ends the hair-springs 2-1 are rotatively secured to the arbor '18 and at their outer ends are connected to lrictionally hold adjustment-levers. The lower or inner adjustment-lever 25 is frietionallv held against support the lower side of the brid e bar 6 by a triotion-disk 26 adjustably old in place by screws, as shown in the drawings.

The upper adjustment-lever 27 is frictionally held against the upper or outer side of the arborjustably held in place by'screws, as shown. The upper and larger friction-disk 28 is slightly elevated above the dial 14 to provide a suitable slot through which the pointer 13 projects from its connection with "the-arborelS to an indicating position above the dial-14;.

Oscillations of the pointer 13 are revented and the instrument rendered ead beat bya magnetically influenced damping device combined directly with and cotiperm tivc with the magnetib bridge 6 and its polepieces 12. This damping device is shown as,

a damping disk 29, which may be of any suitable electrically conductive material,

such aluminum, rotatively carried by the arbor 18 and coil-frame 19 at the lower end of the fr ame 19 and coil 8, so as to lie in proximity to the poles of the magnet 7' and between these poles and the pole-pieces 12 of the bridge bar 6, thus being located in a strong portion of the magnetic field. The damping effect of the damping disk 29 will be proportionately adjusted along with the magnetic adjustment so that this disk will under all conditions and adjustments produce the proper damping etiect. The polepieces 12 are prevented from coming in contact with the damping disk 29 or with the lower hair-spring 24, by means of small limiting pins projecting from the pole-pieces 12, as shown in Figs. 1 and 4', and adapted to engage the bridge bar 6.

The instrument 1s provided with binding posts 30 and 31, shown as extending through the,cylindrical side wall of the front part 32 of the'inclosing case and as insulated therefrom.- The circuit of the instrument may be traced from one of these binding posts through the armature coil 8 back to the other binding post. Starting, for examle, at the post 30 (shown at the right in i ig. .2 and at the left in Fig. 1) the circuit leads from a contact plate 33, by a flexible wire 34, to the free end of the upper adjustmenblever 27, through the upper hair spring, to the armature coil 8. From the coil 8 the circuit continues through the lower hair-spring, to the lower adjustmentlever 25, from the free end of which a flexiblc wire 38tleads to a current-modifying resistance coil 35. secured to the back plate 15 ot the illSi'I'llIlltllt casing, and a flexible conductor 36 connects the other terminal of the resistance 35 with a contact plate '37 con nected to the inner end of the other binding post 31. The resistance coil 35 is employed in a manner well known in the art to secure the original calibration of the instrument.

21 by a larger friction-disk 28- adnation, a'

It is also to be noted that the hair-springs 524i have at their inner ends insulated connection with the arbor 18, as is usual in this type of instrument. c

It is obvious that various modifications may be made in the construction shown in the drawings and above particularly described \vithinthe principle and scope, of my invention. I I

I claim:

1. A galvanometer comprising,- in combination, a-tield magnet, a rotative armature responsive to the magnetic influence of the field magnet, and means forming a magnetic shunt around the end of the armature to modify the influence of the magnetic field uponthe armature. v

"2. A galvanon'ieter comprising, in combinationfa field "magnet, a rotative armature responsive to the magneticfinfluence ofthe field magnet, and means located at the, endpOIiZl on of the armature for weakening tl of the magnetic field occupied by the'armature.

A galvanometer comprising, in combination, a field magnet, a rotative armature responsive to the magnetic influence ofthe field magnet, and means located at the end of the armature for adjusting the strength of that portion of the magnetic field occupied by the armature. h

4. A galvanometer comprisfng, in combination, a: permanent magne a rotative coil rcs 'iousive to the magnetic influence of such magnet, and means for diverting magnetic flux around the end of the 001i.

5. A galvanometcr comprising, in combi-- nation, a permanent inagnet, a rotative coil responsive to the magnetic influence of such magnet, and means located at the d of the coil for modifying the l'nagnetic density of that portion of the field occupied by-the coil. I

MA galvanometer comprising, in combi-- uatim'i, a permanent magnet, a rotative coil responsive to the n'iagnetic influence of such magnet, and means located at the end of the coil for adjusting the strength of that-portion of the magnetic field occupied by the coil.

7. A galvanometer comprising, in combifield magnet having opposed poles producing a magnetic field, a rotative armature in the field and responsive thereto, and a magnetic brid e constituting a support for the armature. i

8. A galvanometer comprising, in combination, a field magnet having opposed poles producing a magnetic field, a rotalivc armature in the field and responsive thereto, and an adjustable magncticbridge forming a pivotal support for the armature. S). A galvanometcr comprising, in 00minnation, a permanentmagnethaving opposed coil located in and responsive to the field, and a magnetic bridge forming a pivotal support for the coil. a i

10. A galv'anometer comprising, in combination, a permanent magnet having opposed poles producing a magnetic field, a rotative coililocated in and responsive to'the field,

and an adjustable magnetic bridge forming a pivotal support for the coil.

ii. A galvanometer c0mprising,-in combination, a permanent magnet having opposed poles producing a magnetic field, a rotative coil located in and responsive to the field, a magnetic bridge for the poles spaced therefrom, and an adjustable pole-piece carried by-the magnetic bridge. i a

12. A galvanometer comprising, in combination, a permanent magnet haviiig opposed polesproducing a magnetic field, a rotative coil located in and responsive to the field, a magnetic bridge =for the poles spaced therefrom, and for each pole a pole-piece carried by the bridge and each indepen lently adjustable to-and. from its corresponding' maguet pole.

13,. A galvanomeier comprising, in combination, a permanent ma gnet having opposed poles producing a magnetiefield, a

,rotative coil located in and responsiveto the field, a magnetic bridge spaced from the magnet poles and located at the end of and forming an axial support for the coil. and pple-pieces carried by the bridge and vadjustable in reference to the magnetpoles.

14-. A galvanometcr comprising, in combination, a permanent magnet having opposed poles producing a magnetic field, a

rotative coil located in and responsive to the field a ma netic brid e for the voles located 7 a r: at the end of and forming an axial supporttor the cm], a non-ma netic su )OI'iI- su l h porting the bridge on the magnet in spaced relation thereto and an ad ustable ole- I u I piece carr ed by the bridge. 15. A galvanou'icter comprising, in combination, a )ermanent ma net havin 2'31 i b posed poles producing a magnetic fieldga rotative coil located in and responsive to the field, a magnetic l'iridge for the poles located at the end of the coil and spaced from the magnet, and a pole-piece smrew-threaded through the bridge so as thereby to be adjustable relatively to a magnet pole.

10.,A galvanometer comprising, in combination, a permanent magnet having opposed-poles producing a magnetic field, a. rotative coil located in and responsive to the field, a magnetic bridge for the poles located at the -end of the coil and forming a pivotal support therefor, a non-magnetic support for the bridge connecting the bridge to the magnet and spacing it therefrom, and polepieces adjustahly screw-threaded through the bridge. 5 1 v 17. A galvanometcr comprising, in combi- *sliunt field around the armature, and a mag netic'ally influenced damping device located "in the shunt field and connected to the armadamping device rotat-ively carried by the ture to rotate therewith. 4 y

19. A galvanometer comprising, in combination, a permanent magnet, arotatlve coil responsive to the magnetic influence of such magnet, means for diverting magnetic flux around the coil, and a magnetically infiuenced damping device cooperative with such means to damp oscillations of the armature. 20. A galvanometer comprising, in combination, a permanent magnet, a rotative coil located in the nmgnetic field and responsive to the magnetic influence of such magnet, means forming an adjustable shunt field around the coil, and a magnetically influenced damping device located in the shunt field and vmovable with the coil. 2-1. A galvanometer comprising, in combination, a field magnet having opposed poles producin'ga magnetic field, a rotat-ive armature in the field and responsive thereto, a damping .glevice rotatively carried by the,

armature, and a magnetic bridge around the end of the armature to modify the magnetic influence to which the armature and the damping device are subjected and forming a pivotal support for the armature.

22. A galvanomctcr comprising, in combi nation, a field magnet having opposed poles producing a magnetic ficld,.a rotative armature in the field and responsive' thereto, a

armature, and an adjustable magnetic bridge around the end of the armature for adjusting the magiietic strength of the field bination, a permanent magnet having op- Y posed poles producing a1. magnetic field, a rotative coil located in land responsive to the field, a magnetic bridge around the end of the coil and forming a pivotal support for the coil, an'dta damping plate rotatively carried by the coil between a magnet pole and the bridge. u

24. A galvanometer" comprising, in combination; a permanent magnet having opposed poles producing a magnetic field,ya rotative coil located in and responsive to the field, an adjustable magnetic bridge around the end of the coil and forming a pivotal support therefor, and a damping plate ro tatively carried by .the coil between a magnet p'ole and such bridge.

25. A galvano-meter comprising, in combination, a permanent magnet having opposed poles producing a magnetic field, a magnetic bridge for the poles spaced from the magnet, an adjustable pole-piece carried by such bridge, and a damping plate rotatively carried by the coil between'a magnet pole and the adjustable pole-piece.

26. A galvanometer comprising, in combination, a permanent magnet having opposed poles producinga magnetic field, a rotative coil located in and responsive to the field, a magnetic bridge for the poles lo= cated at the end of the coil and forming a pivotal support therefor, a non-magnetic support for the bridge connecting the bridge to and spacingyit from the magnet, for each magnet pole anflindependently' adjustable 

